function y = pq(x)
%Perturbed Quadratic function 
%x0=[0.5, 0.5,..., 0.5].
%fmin=n/2
%Author:shi yangyang
n=length(x);
t=ones(1,n);
q=ones(1,n);
for i=1:1:n
    t(i)=i*(x(i)^2);
end
t=sum(t);
for i=1:n
    q(i)=x(i);
end
q=sum(q);
y=t+0.01*(q^2);